The present invention is directed to an improved system and method for welding projection weld nuts. More particularly, the present invention is directed to a robotic system and method for welding projection weld nuts.
Projection weld nuts would be well known to one skilled in the art. However, in brief, projection weld nuts are generally threaded nuts designed especially for attachment to a metallic work piece via resistance welding. To facilitate welded attachment, projection weld nuts include several portions of weld material that project outward from a welding face (i.e., the face of the projection weld nut that will contact the work piece). The projection weld nut is placed into contact with a work piece, typically in or over a pilot hole, pressure is preferably applied, and a resistance welding apparatus is used to pass current through the work piece and the projection weld nut. The current causes a melting of the weld material projections and a welding of the projection weld nut to the work piece.
In a typical projection weld nut welding process, a projection weld nut is located to a work piece for welding. The work piece is often maintained in the welding position by hand. Welding is typically accomplished by use of a specialized resistance welding device that includes a pair of electrodes designed to apply pressure to the projection weld nut and work piece and to pass current through the work piece and the projection weld nut. For example, a first electrode may be provided to contact an underside of the work piece while a second electrode is provided to contact the projection weld nut. Each of the electrodes is normally pressed against the work piece by an actuator, such as a hydraulic or pneumatic cylinder.
The problem with such a system is that it requires specialized equipment unique to the work piece at issue, and also commonly necessitates much handling by an operator. Applicant is unaware of any existing system or process for attaching projection welding nuts to a work piece using a common resistance (e.g., spot) welding robot. The ability to weld projection weld nuts using a resistance welding robot would, therefore, be desirable—as such a robot can be easily adapted for use with work pieces of varying size and/or shape, thereby obviating the need for a specialized resistance welding apparatus and also minimizing operator handling.
The present invention is such a system and process. That is, the present invention is directed to a system and process for welding projection welding nuts, whereby the welding process is accomplished using a resistance welding robot.